翘嘴红鲌雌雄基因组差异及太湖野生群体遗传多样性现状的AFLP分析

AFLP ANALYSIS ON GENOMIC SEXUAL DIMORPHISM OF ERYTHROCULTER ILISHAEFORMIS AND CURRENT GENETIC DIVERSITY OF THE TAIHU STRAIN

为发展翘嘴红鲌Erythroculter ilishaeformis(Bleeker)性别控制育种和单性养殖技术,利用AFLP技术对翘嘴红鲌太湖野生群体中雌、雄各20个个体的基因组进行了遗传多样性和雌雄差异分析。用筛选出的8对AFLP多态性引物在太湖野生群体基因组中共检测到319个位点,其中多态性位点185个。通过对所有多态性位点在个体中的分布进行分析,发现一个只在雄性个体中稳定存在、在雌性个体中缺失的差异位点。在人工雌核发育翘嘴红鲌群体只有雌性个体,其基因组中也检测不到该差异位点的存在。这些结果表明翘嘴红鲌性别分化可能受到严格的遗传调控,该差异位点是雄性特有的性别分子标记。翘嘴红鲌太湖野生群体目前的多态位点比率P=57.99%,观测等位基因数N_a=1.5799±0.4943,有效等位基因数N_e=1.3859±0.3971,Shannon’s信息指数I=0.3221±0.2987。这些统计分析结果与10年前对该群体的AFLP研究结果(P=51.21%,Na=1.512±0.500,Ne=1.252±0.371,I=0.218±0.275)相比没有显著差别(P>0.05),说明该群体目前还具有适度的遗传多样性。

The Taihu strain of Erythroculter ilishaeformis is a premium aquaculture species and is now widely cultivated in the Yangtze River Delta freshwater region. Under captivity, sexual dimorphism in somatic growth is very common with female being faster grower and having larger body size compared with male. Therefore, manipulating sex for all-female population of E. ilishaeformis can substantially increase aquaculture production and economic benefits.However, the key regulatory genes and mechanisms affecting sex determination and differentiation of E. ilishaeformis are still unclear and no gender-related molecular marker has been reported yet. Consequently, developing the technique for the monosexual production of E. ilishaeformis remains difficult in the breeding program at present. To develop the technology, the genetic diversity and genomic sexual dimorphism of the Taihu strain were analyzed by AFLP（amplified fragment length polymorphism） molecular marker technique. The sampling size was 20 male and 20 female individuals, respectively. A total of 319 loci were detected using 8 pairs of polymorphic primers. Of the 319 detected loci,185 loci displayed polymorphism. By analyzing the distribution of the polymorphic loci in all the examined individuals,we discovered a locus that was only existing among male individuals and was absent among females. In consistent with this observation, no male individual was detected in the artificial gynogenetic group of the E. ilishaeformis, and the locus was not detected in the genome of all examined gynogenetic individuals. The results suggested that sex determination and differentiation in this species may be strictly controlled by genes located in that specific region, and that gender difference locus we detected can be used as a male-specific marker. Our statistical analysis showed that the percentage of polymorphic loci of Taihu strain was 57.99%, the observed number of alleles of Taihu strain was1.5799±0.4943, the effective number of alleles of Taihu strain was 1.3859±0.3971, and the Shannon＇s information index of the population was 0.3221±0.2987. These data indicated that the genetic diversity of Taihu strain is moderate and is maintained at a similar level（P=51.21%, Na=1.512±0.500, Ne=1.252±0.371, I=0.218±0.275） compared with the results obtained 10 years ago.